As filed with the Securities and Exchange Commission on January 18, 2013

Registration No.
333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Dune Energy, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware

1389

95-4737507

(State or Other Jurisdiction of

Incorporation or Organization)

(Primary Standard IndustrialClassification Code Number)

(I.R.S. Employer

Identification Number)

Two Shell Plaza

777 Walker Street, Suite 2300

Houston, Texas 77002

(713) 229-6300

(Address, including Zip Code, and Telephone Number, including Area Code, of Registrants Principal Executive Offices)

James A. Watt

President and Chief Executive Officer

Two Shell Plaza

777 Walker Street, Suite 2300

Houston, Texas 77002

(713) 229-6300

(Name, Address, including Zip Code, and Telephone Number, including Area Code, of Agent for Service)

Copies to:

Paul Hurdlow

Philip Russell

DLA Piper LLP (US)

401 Congress, Suite 2500

Austin, Texas 78701

(512) 457-7000

Approximate
date of commencement of proposed sale to the public: From time to time after this Registration Statement becomes effective.

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, check the following box. x

If
this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement
for the same offering. ¨

If this form is a
post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same
offering. ¨

If this form is a post-effective amendment
filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an
accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of large accelerated filer, accelerated filer and smaller reporting company in Rule 12b-2 of the Exchange Act:

Large accelerated filer

¨

Accelerated filer

¨

Non-accelerated filer

¨ (Do not check if a smaller reporting company)

Smaller reporting company

x

CALCULATION OF REGISTRATION FEE

Title Of Each Class Of

Securities To Be Registered

Amount

to be

Registered(1)

Proposed

MaximumAggregate

Offering Price

Per Share(1)(2)

Proposed

MaximumAggregate

Offering Price(2)

Amount ofRegistration Fee

Common stock, par value $0.001 per share

18,749,997

$1.625

$30,468,745.13

$4,155.94

(1)

Represents shares offered by the selling shareholders named in this registration statement, including 18,749,997 shares of the registrants common stock issued to
the shareholders pursuant to Common Stock Purchase Agreements between the registrant and each of the selling shareholders dated December 20, 2012 (the Stock Purchase Agreements).

(2)

Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(c) under the Securities Act of 1933, as amended. The calculation of the
proposed maximum aggregate offering price of the common stock is based on the average of the bid and asked prices for the common stock on January 15, 2013.

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until
the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall
become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and is subject to change. We may not sell
these securities until the registration statement filed with the Securities and Exchange Commission of which this prospectus is a part is declared effective. This prospectus does not constitute an offer to sell, or a solicitation of an offer to buy
the securities in any jurisdiction where the offer or solicitation is not permitted.

Subject to Completion, Dated January 18, 2013

18,749,997 Shares of Common Stock

This prospectus relates to the resale of up to 18,749,997 shares of common stock, par value $0.001 per share, of Dune Energy, Inc. (the
common stock) offered by the selling shareholders named in this registration statement which represents shares of the registrants common stock issued to the shareholders pursuant to Common Stock Purchase Agreements between
the registrant and each of the selling shareholders dated December 20, 2012 (the Stock Purchase Agreements). The common stock offered hereby may be offered for sale from time to time by the selling stockholders named in this
prospectus.

The selling stockholders and their permitted transferees may offer and sell the common stock offered hereby from
time to time at market prices, in negotiated transactions or otherwise. The timing and amount of any sale are within the sole discretion of the selling stockholders. The selling stockholders may sell the common stock offered hereby directly or
through underwriters, brokers or dealers or through a combination of these methods. The selling stockholders will pay commissions or discounts to underwriters, brokers or dealers in amounts to be negotiated prior to the sale. We will not receive any
of the proceeds from the sale of the common stock offered by the selling stockholders. See Plan of Distribution on page 21 for more information on this topic.

Our common stock is traded on the OTC Bulletin Board under the symbol DUNR. On January 15, 2013, the closing price of our common stock on the bulletin board was $1.64.

Investing in our common stock being offered for resale under this prospectus involves a high degree of risk. See
Risk Factors beginning on page 7 before you make an investment in our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the common stock or passed upon the adequacy or accuracy of this prospectus. Any
representation to the contrary is a criminal offense.

You should rely
only on the information contained in this prospectus and incorporated by reference herein. We have not authorized anyone to provide you with information that is different. This prospectus does not constitute an offer to sell, or a solicitation of an
offer to buy the securities in any circumstances under which the offer or solicitation is not permitted. You should not assume that the information contained in this prospectus is accurate as of any date other than the date hereof, regardless of the
time of delivery of this prospectus or of any sale of the common stock being registered in the registration statement of which this prospectus forms a part.

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, utilizing a
shelf registration process. Under this shelf registration process, the selling stockholders may sell the securities described in this prospectus in one or more offerings. This prospectus does not contain all of the information included
in the registration statement. The registration statement filed with the SEC includes exhibits that provide more details about the matters discussed in this prospectus. You should carefully read this prospectus and the information incorporated by
reference herein and any prospectus supplement, the related exhibits filed with the SEC, together with the additional information described below under the headings Where You Can Find More Information.

You should rely only on the information contained in this prospectus and the information incorporated by reference herein. We have
not, and the selling stockholders have not, authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. The selling stockholders are not making
offers to sell or seeking offers to buy any of the securities covered by this prospectus in any state where the offer is not permitted. You should assume that the information appearing in this prospectus is accurate only as of the date on the front
cover of this document. Our business, financial condition, results of operations and prospects may have changed since this date.

Under no circumstances should the delivery to you of this prospectus or any offer or sale made pursuant to this prospectus create any implication that the information contained in this prospectus is
correct as of any time after the date of this prospectus.

Unless otherwise indicated or unless the context otherwise
requires, all references in this prospectus to Dune, the Company, the Registrant, we, us, and our mean Dune Energy, Inc. and its
subsidiaries.

WHERE YOU CAN FIND MORE INFORMATION

We have filed a registration statement with the SEC under the Securities Act of 1933, as amended, which we refer to as the Securities
Act, that registers the resale by the selling stockholders of the securities offered by this prospectus. The registration statement, including the attached exhibits, contains additional relevant information about us. The rules and regulations of the
SEC allow us to omit some information included in the registration statement from this prospectus.

We file annual, quarterly,
and other reports, proxy statements and other information with the SEC under the Securities Exchange Act of 1934, as amended, which we refer to as the Exchange Act. You may read and copy any materials we file with the SEC at the SECs public
reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. Our SEC filings are also available to the public through the SECs website at
http://www.sec.gov. General information about us, including our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, as well as any amendments and exhibits to those reports, are available free of charge
through our website at http://www.duneenergy.com as soon as reasonably practicable after we file them with, or furnish them to, the SEC. Information on our website is not incorporated into this prospectus or our other securities filings and
is not a part of this prospectus.

The Company desires to take advantage of the safe harbor provisions of the Private Securities Litigation
Reform Act of 1995. This prospectus contains a number of forward-looking statements that reflect managements current views and expectations with respect to our business, strategies, future results and events and financial performance. All
statements made in this prospectus other than statements of historical fact, including statements that address operating performance, events or developments that management expects or anticipates will or may occur in the future, including statements
related to revenues, cash flow, profitability, adequacy of funds from operations, statements expressing general optimism about future operating results and non-historical information, are forward looking statements. In particular, the words
believe, expect, intend, anticipate, estimate, may, will, variations of such words, and similar expressions identify forward-looking statements, but are not the
exclusive means of identifying such statements and their absence does not mean that the statement is not forward-looking. These forward-looking statements are subject to certain risks and uncertainties, including those discussed under Risk
Factors and elsewhere in this prospectus. Our actual results, performance or achievements could differ materially from historical results as well as those expressed in, anticipated or implied by these forward-looking statements.

Readers should not place undue reliance on these forward-looking statements, which are based on managements current expectations
and projections about future events, are not guarantees of future performance, are subject to risks, uncertainties and assumptions (including, without limitation, those described herein) and apply only as of the date of this prospectus. Our actual
results, performance or achievements could differ materially from the results expressed in, or implied by, these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed
below in Risk Factors as well as those discussed elsewhere in this prospectus, and the risks discussed in our press releases and other communications to stockholders issued by us from time to time which attempt to advise interested
parties of the risks and factors that may affect our business. Except as may be required under the federal securities laws, we undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new
information, future events or otherwise.

GLOSSARY OF OIL AND GAS TERMS

The following are abbreviations and definitions of certain terms commonly used in the oil and gas industry and this prospectus:

Bbl. One stock tank barrel, or 42 U.S. gallons liquid volume, used in reference to oil or other liquid hydrocarbons.

Bcf. One billion cubic feet of gas.

Bcfe. One billion cubic feet of natural gas equivalent, using the ratio of one barrel of crude oil, condensate or natural gas liquids to 6 Mcf of natural gas.

Boe. One barrel of oil equivalent, using the ratio of one barrel of crude oil, condensate or natural gas liquids to 6 Mcf of
natural gas.

Btu. British thermal unit. One British thermal unit is the amount of heat required to raise the
temperature of one pound of water by one degree Fahrenheit.

Developed oil and gas reserves. Developed oil and gas
reserves are reserves of any category that can be expected to be recovered: (i) through existing wells with existing equipment and operating methods or in which the cost of the required equipment is relatively minor compared to the cost of a
new well; and (ii) through installed extraction equipment and infrastructure operational at the time of the reserves estimate if the extraction is by means not involving a well.

Development well. A well drilled within the proved area of an oil or gas reservoir to
the depth of a stratigraphic horizon known to be productive.

Differential. An adjustment to the price of oil or gas
from an established spot market price to reflect differences in the quality or location of oil or gas.

Exploratory
well. A well drilled to find a new field or to find a new reservoir in a field previously found to be productive of oil or gas in another reservoir. Generally, an exploratory well is any well that is not a development well, an extension well, a
service well or a stratigraphic test well.

Extension well. An extension well is a well drilled to extend the limits of
a known reservoir.

Gas. Natural gas.

MBbl. One thousand barrels of crude oil or other liquid hydrocarbons.

Mcf. One thousand cubic feet of gas.

Mcfe. One thousand cubic feet of gas equivalent, using the ratio of one barrel of crude oil, condensate or natural gas liquids to 6 Mcf of natural gas.

Mmbbls. One million barrels of crude oil or other liquid hydrocarbons.

Mmbtu. One million Btus.

Mmcf. One million cubic feet of gas.

MMcfe. One million cubic feet
of gas equivalent.

Oil. Crude oil, condensate and natural gas liquids.

Operator. The individual or company responsible for the exploration or production of an oil or gas well or lease.

PV-10. The after tax present value of estimated future cash flow of proved reserves. The calculation is based on current commodity
prices and is discounted at 10%.

This summary highlights information contained elsewhere in this prospectus. This summary does not contain all of the information you
should consider before investing in our common stock. You should read this entire prospectus carefully, including without limitation the Risk Factors section of this prospectus, and the documents incorporated by reference herein,
including our consolidated financial statements and related notes, before making an investment decision. Some of the statements in this prospectus and the documents incorporated by reference herein constitute forward-looking statements. See
Cautionary Notice Regarding Forward-Looking Statements for more information.

Our Company

Dune Energy, Inc., a Delaware corporation, is an independent energy company based in Houston, Texas. We were formed in 1998 and since May
of 2004, we have been engaged in the exploration, development, acquisition and exploitation of crude oil and natural gas properties, with interests along the Louisiana/Texas Gulf Coast. Our properties cover over 86,000 gross acres across 22
producing oil and natural gas fields.

Our total proved reserves as of June 30, 2012 were 96.5 Bcfe (16.1 Mboe),
consisting of 54.4 Bcf of natural gas and 7.0 Mmbbls of oil. The PV-10 of our proved reserves at June 30, 2012 was $309.1 million based on the average of the oil and natural gas sales prices on the first day of each of the twelve months ended
June 2012, which was $110.37 per bbl of oil and $3.37 per mcf of natural gas.

Our Business Strategy

We intend to use our competitive strengths to increase reserves, production and cash flow in order to maximize value for our stockholders.
The following are key elements of this strategy:

Grow Through Exploitation, Development and Exploration of Our
Properties. Our primary focus will continue to be the development and exploration efforts in our Gulf Coast properties. We believe that our properties and acreage position will allow us to grow organically through low-risk drilling in the near
term, as this property set continues to present attractive opportunities to expand our reserve base through workovers and recompletions, field extensions, delineating deeper formations within existing fields and higher risk/higher reward exploratory
drilling. In addition, we will constantly review, rationalize and high-grade our properties in order to optimize our existing asset base.

Actively Manage the Risks and Rewards of Our Drilling Program. Our strategy is to increase our oil and natural gas reserves and production while keeping our finding and development costs and
operating costs (on a per Mcfe basis) competitive with our industry peers. We expect to implement this strategy through drilling exploratory and development wells from our inventory of available prospects that we have evaluated for geologic and
mechanical risk and future reserve or resource potential. Our drilling program will contain some higher risk/higher reserve potential opportunities as well as some lower risk/lower reserve potential opportunities in order to achieve a balanced
program of reserve and production growth.

Maintain and Utilize State of the Art Technological Expertise. We expect to
maintain and utilize our technical and operations teams knowledge of salt-dome structures and multiple stacked producing zones common in the Gulf Coast to enhance our growth prospects and reserve potential. We employ technical advancements,
including 3-D seismic data, pre-stack depth and reverse-time migration, to identify and exploit new opportunities in our asset base. We also employ the latest directional drilling, completion and stimulation technology in our wells to enhance
recoverability and accelerate cash flows.

a minimum of initial upfront capital. We are also seeking to acquire operational control of properties that we believe have a solid proved reserve base coupled with significant exploitation and
exploration potential. We will evaluate acquisition opportunities that we believe will further enhance our operations and reserves in a cost-effective manner.

Summary Risk Factors

We are subject to a number of risks, including risks
that may prevent us from achieving our business objectives or may adversely affect our business, financial condition, results of operations, cash flows and prospects. You should carefully consider these risks, including all of the risks discussed in
the section entitled Risk Factors, beginning on page 7 of this prospectus and discussed in the documents incorporated by reference herein, before investing in our common stock. Risks relating to our business include, among others:



We have had operating losses and limited revenues to date.



We have substantial capital requirements that, if not met, may hinder our operations.

Drilling for natural gas and oil is a speculative activity and involves numerous risks and substantial and uncertain costs that could adversely affect
us.



We depend on successful exploration, development and acquisitions to maintain reserves and revenue in the future.



Our estimated reserves are based on many assumptions that may prove inaccurate. Any material inaccuracies in these reserve estimates or underlying
assumptions will materially affect the quantities and present value of our reserves.

Our principal offices are located at Two Shell Plaza, 777 Walker Street, Suite 2300, Houston, Texas 77022. We can be reached by phone at 713-229-6300 and our website address is www.duneenergy.com.
Information on our website is not part of this prospectus.

An investment in our common stock is subject to numerous risks, including those listed below and described elsewhere in this
prospectus and the documents incorporated by reference herein. You should carefully consider these risks, along with the information provided elsewhere in this prospectus and the documents incorporated by reference herein before investing in the
common stock. You could lose all or part of your investment in the common stock.

We have had operating losses and
limited revenues to date.

We have operated at a loss each year since inception. Net losses applicable to common
stockholders for the fiscal years ended December 31, 2010 and 2011 were $101.9 million and $80.6 million, respectively. Our revenues for the fiscal years ended December 31, 2010 and 2011 were $64.2 million and $62.9 million, respectively.
We may not be able to generate significant revenues in the future. In addition, we expect to incur substantial operating expenses in connection with our natural gas and oil exploration and development activities. As a result, we may continue to
experience negative cash flow for at least the foreseeable future and cannot predict if or when we might become profitable.

Our New Credit Agreement imposes significant operating and financial restrictions on us that may prevent us from pursuing certain
business opportunities and restrict our ability to operate our business.

Our Amended and Restated Credit Agreement
(the New Credit Agreement) contains covenants that restrict our ability and the ability of certain of our subsidiaries to take various actions, such as:



have a leverage ratio of greater than 4.0 to 1.0;



have a current ratio of less than 1.0 to 1.0;



incur additional debt;



make distributions or other restricted payments;



make investments;



change its business;



enter into leases;



use the proceeds of loans other than as permitted by the New Credit Agreement;



sell receivables;



merge or consolidate or sell, transfer, lease or otherwise dispose of its assets;



sell properties and terminate hedges in excess of 5% of the borrowing base then in effect;



enter into transactions with affiliates of the Company;



organize subsidiaries;



agree to limit its ability to grant liens or pay dividends;



incur gas imbalances or make prepayments;



enter into hedge agreements in excess of agreed limits;



modify its organizational documents; and



engage in certain types of hydrocarbon marketing activities.

The New Credit Agreement also contains other customary covenants that, subject to certain exceptions, include, among other things:
maintenance of existence; maintenance of insurance; compliance with laws;

delivery of certain information; maintenance of properties; keeping of books and records; preservation of organizational existence; and further assurances requirements.

The restrictions contained in the New Credit Agreement could:



limit our ability to plan for or react to market conditions or meet capital needs or otherwise restrict our activities or business plans; and



adversely affect our ability to finance our operations, strategic acquisitions, investments or alliances or other capital needs or to engage in other
business activities that would be in our interest.

We have substantial capital requirements that, if
not met, may hinder our operations.

We have and expect to continue to have substantial capital needs as a result of
our active exploration, development and acquisition programs. We expect that additional external financing will be required in the future to fund our growth. We may not be able to obtain additional financing, and financing under our new credit
facility pursuant to the New Credit Agreement may not be available in the future. Without additional capital resources, we may be forced to limit or defer our planned natural gas and oil exploration and development program and this will adversely
affect the recoverability and ultimate value of our natural gas and oil properties, which will in turn negatively affect our business, financial condition, and results of operations.

The disruption experienced in U.S. and global credit markets since the latter half of 2008 has resulted in instability in demand for oil
and natural gas, resulting in volatile energy prices, and has affected the availability and cost of capital. In addition, capital and credit markets have experienced unprecedented volatility and disruption and continue to be unpredictable. Given the
current levels of market volatility and disruption, the availability of funds from those markets has diminished substantially. Prolonged negative changes in domestic and global economic conditions or disruptions of the financial or credit markets
may have a material adverse effect on our results from operations, financial condition and liquidity. At this time, it is unclear whether and to what extent the actions taken by the U.S. government will mitigate the effects of the financial market
turmoil. The impact of the current difficult conditions on our ability to obtain, and the cost and terms of, any financing in the future is equally unclear. Any inability to obtain adequate financing under our new credit facility or to fund on
acceptable terms could deter or prevent us from meeting our future capital needs to finance our development program, adversely affect the satisfaction or replacement of our debt obligations and result in a deterioration of our financial condition.

Our revenue, profitability, cash flow, oil and natural gas reserves value, future growth, and ability to borrow funds
or obtain additional capital, as well as the carrying value of our properties, are substantially dependent on prevailing prices of natural gas and oil. Historically, the markets for natural gas and oil have been volatile, and those markets are
likely to continue to be volatile in the future. It is impossible to predict future natural gas and oil price movements with certainty. Prices for natural gas and oil are subject to wide fluctuations in response to relatively minor changes in the
supply of and demand for natural gas and oil, market uncertainty, and a variety of additional factors beyond our control. These factors include, but are not limited to:

political conditions in or affecting oil and natural gas producing regions;



the level and price of foreign imports of oil and liquefied natural gas; and



the ability of the members of the Organization of Petroleum Exporting Countries and other state controlled oil companies to agree upon and maintain oil
price and production controls.

Declines in natural gas and oil prices may materially adversely affect our
financial condition, liquidity, and ability to finance planned capital expenditures and results of operations and may reduce the amount of oil and natural gas that we can produce economically.

Drilling for natural gas and oil is a speculative activity and involves numerous risks and substantial and uncertain costs that
could adversely affect us.

Our success will be largely dependent upon the success of our drilling program. Our
prospects are in various stages of evaluation, ranging from prospects that are ready to drill to prospects that will require substantial additional seismic data processing and interpretation and other types of technical evaluation. There is no way
to predict in advance of drilling and testing whether any particular prospect will yield oil or natural gas in sufficient quantities to recover drilling or completion costs or to be economically viable. The use of seismic data and other technologies
and the study of producing fields in the same area will not enable us to know conclusively prior to drilling whether oil or natural gas will be present or, if present, whether oil or natural gas will be present in commercial quantities. We cannot
assure you that the analogies we draw from available data from other wells, more fully explored prospects or producing fields will be applicable to our drilling prospects. Drilling for natural gas and oil involves numerous risks, including the risk
that no commercially productive natural gas or oil reservoirs will be discovered. The cost of drilling, completing, and operating wells is substantial and uncertain, and drilling operations may be curtailed, delayed, or canceled as a result of a
variety of factors beyond our control, including:



unexpected or adverse drilling conditions;



elevated pressure or irregularities in geologic formations;



equipment failures or accidents;



adverse weather conditions;



compliance with governmental requirements; and



shortages or delays in the availability of drilling rigs, crews and equipment.

Even if drilled, our completed wells may not produce reserves of natural gas or oil that are economically viable or that meet our earlier
estimates of economically recoverable reserves. A productive well may become uneconomic if water or other deleterious substances are encountered, which impair or prevent the production of oil or natural gas from the well. Our overall drilling
success rate or our drilling success rate for activity within a particular project area may decline. Unsuccessful drilling activities could result in a significant decline in our production and revenues and materially harm our operations and
financial condition by reducing our available cash and resources. Because of the risks and uncertainties of our business, our future performance in exploration and drilling may not be comparable to our historical performance.

We depend on successful exploration, development and acquisitions to maintain reserves and revenue in the future.

In general, the volume of production from natural gas and oil properties declines as reserves are depleted, with the
rate of decline depending on reservoir characteristics. Except to the extent that we conduct successful exploration and development activities or acquire properties containing proved reserves, or both, our proved reserves will decline as reserves
are produced. Our future natural gas and oil production is, therefore, highly

dependent on our level of success in finding or acquiring additional reserves. Additionally, the business of exploring for, developing, or acquiring reserves is capital intensive. Recovery in our
reserves, particularly undeveloped reserves, will require significant additional capital expenditures and successful drilling operations. To the extent cash flow from operations is reduced and external sources of capital become limited or
unavailable, our ability to make the necessary capital investment to maintain or expand our asset base of natural gas and oil reserves would be impaired. In addition, we are dependent on finding partners for our exploratory activity and to the
extent that others in the industry do not have the financial resources or choose not to participate in our exploration activities, we will be adversely affected.

Our estimated reserves are based on many assumptions that may prove inaccurate. Any material inaccuracies in these reserve estimates or underlying assumptions will materially affect the quantities
and present value of our reserves.

No one can measure underground accumulations of oil and natural gas in an exact
way. Oil and natural gas reserve engineering requires subjective estimates of underground accumulations of oil and natural gas and assumptions concerning future oil and natural gas prices, production levels, and operating and development costs. As a
result, estimated quantities of proved reserves and projections of future production rates and the timing of development expenditures may prove to be inaccurate. Any material inaccuracies in these reserve estimates or underlying assumptions will
materially affect the quantities and present value of our reserves which could adversely affect our business, results of operations and financial condition.

Further, the present value of future net cash flows from our proved reserves may not be the current market value of our estimated natural gas and oil reserves. In accordance with SEC requirements, we base
the estimated discounted future net cash flows from our proved reserves on the 12-month average oil and gas index prices, calculated as the unweighted arithmetic average for the first-day-of-the-month price for each month and costs in effect on the
date of the estimate, holding the prices and costs constant throughout the life of the properties. Actual future prices and costs may differ materially from those used in the net present value estimate, and future net present value estimates using
then current prices and costs may be significantly less than the current estimate. In addition, the 10% discount factor we use when calculating discounted future net cash flows for reporting requirements in compliance with FASB ASC 932 may not be
the most appropriate discount factor based on interest rates in effect from time to time and risks associated with us or the natural gas and oil industry in general.

As of the end of our 2011 fiscal year, approximately 35% of our proved reserves were classified as proved undeveloped reserves. These reserves may not ultimately be developed or produced. As a result, we
may not find commercially viable quantities of oil and natural gas, which in turn may have a material adverse effect on our results of operations.

Seismic studies do not guarantee that hydrocarbons are present or, if present, will produce in economic quantities.

We rely on seismic studies to assist us with assessing prospective drilling opportunities on our properties, as well as on properties that we may acquire. Such seismic studies are merely an interpretive
tool and do not necessarily guarantee that hydrocarbons are present or if present will produce in economic quantities.

We may experience difficulty in achieving and managing future growth.

Future growth may place strains on our resources and cause us to rely more on project partners and independent contractors, possibly
negatively affecting our financial condition and results of operations. Our ability to grow will depend on a number of factors, including, but not limited to:



our ability to obtain leases or options on properties for which we have 3-D seismic data;

our ability to maintain or enter into new relationships with project partners and independent contractors;



the results of our drilling program;



hydrocarbon prices; and



our access to capital.

We may not be successful in upgrading our technical, operations, and administrative resources or in increasing our ability to internally provide certain of the services currently provided by outside
sources, and we may not be able to maintain or enter into new relationships with project partners and independent contractors. Our inability to achieve or manage growth may adversely affect our financial condition and results of operations.

Our business may suffer if we lose key personnel.

We depend to a large extent on the services of certain key management personnel, including James A. Watt, our President and Chief
Executive Officer, Frank T. Smith, Jr., our Senior Vice President and Chief Financial Officer, and our other executive officers and key employees. The loss of Mr. Watt, Mr. Smith or other key management personnel could have a material
adverse effect on our business, financial condition and results of operations. These individuals have extensive experience and expertise in evaluating and analyzing producing oil and natural gas properties and drilling prospects, maximizing
production from oil and natural gas properties, marketing oil and natural gas production and developing and executing financing and hedging strategies. We do not maintain key-man life insurance with respect to any of our employees. Our success will
be dependent on our ability to continue to employ and retain skilled technical personnel.

We face strong competition
from other natural gas and oil companies.

We encounter competition from other natural gas and oil companies in all
areas of our operations, including the acquisition of exploratory prospects and proved properties. Our competitors include major integrated natural gas and oil companies and numerous independent natural gas and oil companies, individuals, and
drilling and income programs. Many of our competitors are large, well-established companies that have been engaged in the natural gas and oil business much longer than we have and possess substantially larger operating staffs and greater capital
resources than we do. These companies may be able to pay more for exploratory projects and productive natural gas and oil properties and may be able to define, evaluate, bid for, and purchase a greater number of properties and prospects than our
financial or human resources permit. In addition, these companies may be able to expend greater resources on the existing and changing technologies that we believe are and will be increasingly important to attaining success in the industry. We may
not be able to conduct our operations, evaluate, and select suitable properties and consummate transactions successfully in this highly competitive environment.

We may not be able to keep pace with technological developments in our industry.

The natural gas and oil industry is characterized by rapid and significant technological advancements and introductions of new products and services using new technologies. As others use or develop new
technologies, we may be placed at a competitive disadvantage or competitive pressures may force us to implement those new technologies at substantial costs. In addition, other natural gas and oil companies may have greater financial, technical, and
personnel resources that allow them to enjoy technological advantages and may in the future allow them to implement new technologies before we can. We may not be able to respond to these competitive

pressures and implement new technologies on a timely basis or at an acceptable cost. If one or more of the technologies we use now or in the future were to become obsolete or if we are unable to
use the most advanced commercially available technology, our business, financial condition, and results of operations could be materially adversely affected.

Natural gas and oil operations are subject to various federal, state and local government regulations that may change from time to time.
Matters subject to regulation include discharge permits for drilling operations, plug and abandonment bonds, reports concerning operations, the spacing of wells, unitization and pooling of properties and taxation. From time to time, regulatory
agencies have imposed price controls and limitations on production by restricting the rate of flow of natural gas and oil wells below actual production capacity in order to conserve supplies of natural gas and oil. Other federal, state and local
laws and regulations relating primarily to the protection of human health and the environment apply to the development, production, handling, storage, transportation and disposal of natural gas and oil, by-products thereof and other substances and
materials produced or used in connection with natural gas and oil operations. In addition, we may be liable for environmental damages caused by previous owners of property we purchase or lease. Some environmental laws provide for joint and several
strict liability for remediation of releases of hazardous substances, rendering a person liable for environmental damage without regard to negligence or fault on the part of such person. In addition, we may be subject to claims alleging personal
injury or property damage as a result of alleged exposure to hazardous substances such as oil and natural gas related products. As a result, we may incur substantial liabilities to third parties or governmental entities and may be required to incur
substantial remediation costs. We also are subject to changing and extensive tax laws, the effects of which cannot be predicted. Compliance with existing, new or modified laws and regulations could have a material adverse effect on our business,
financial condition and results of operations.

Certain federal income tax deductions currently available with respect
to oil and natural gas drilling and development may be eliminated as a result of future legislation.

President
Obamas Fiscal Year 2013 Budget includes proposals that would, if enacted into law, make significant changes to United States tax laws, including the elimination of certain key U.S. federal income tax incentives currently available to oil and
natural gas exploration and production companies. These changes include, but are not limited to, (i) the repeal of the percentage depletion allowance for oil and natural gas properties, (ii) the elimination of current deductions for
intangible drilling and development costs, (iii) the elimination of the deduction for certain domestic production activities and (iv) increasing the amortization period for certain geological and geophysical expenditures. It is unclear
whether these or similar changes will be enacted and, if enacted, how soon any such changes could become effective. The passage of any legislation as a result of these proposals or any other similar changes in U.S. federal income tax laws could
eliminate or postpone certain tax deductions that are currently available with respect to oil and natural gas exploration and development, and any such change could increase our tax liability and negatively impact our financial results.

We may not have enough insurance to cover all of the risks we face and operators of prospects in which we participate may not
maintain or may fail to obtain adequate insurance.

In accordance with customary industry practices, we maintain
insurance coverage against some, but not all, potential losses in order to protect against the risks we face. We do not carry business interruption insurance. We may elect not to carry insurance if our management believes that the cost of available
insurance is excessive relative to the risks presented. In addition, we cannot insure fully against pollution and environmental risks. The occurrence of an event not fully covered by insurance could have a material adverse effect on our financial
condition and results of operations. The impact of hurricanes in the areas where we operate has resulted in escalating insurance costs and less favorable coverage terms.

Oil and natural gas operations are subject to particular hazards incident to the drilling
and production of oil and natural gas, such as blowouts, cratering, explosions, uncontrollable flows of oil, natural gas or well fluids, fires and pollution and other environmental risks. These hazards can cause personal injury and loss of life,
severe damage to and destruction of property and equipment, pollution or environmental damage and suspension of operation. We do not operate all of the properties in which we have an interest. In the projects in which we own a non-operating interest
directly, the operator for the prospect maintains insurance of various types to cover our operations with policy limits and retention liability customary in the industry. We believe the coverage and types of insurance are adequate. The occurrence of
a significant adverse event that is not fully covered by insurance could result in the loss of our total investment in a particular prospect which could have a material adverse effect on our financial condition and results of operations.

The financial condition of our operators could negatively impact our ability to collect revenues from operations.

We operate the majority of the properties in which we have working interests. In the event that an operator of our
remaining properties experiences financial difficulties, this may negatively impact our ability to receive payments for our share of net production to which we are entitled under our contractual arrangements with such operator. While we seek to
minimize such risk by structuring our contractual arrangements to provide for production payments to be made directly to us by first purchasers of the hydrocarbons, there can be no assurances that we can do so in all situations covering our
non-operated properties.

We may hedge the price risks associated with our production. Our hedge transactions may result
in our making cash payments or prevent us from benefiting to the fullest extent possible from increases in prices for natural gas and oil.

Because natural gas and oil prices are unstable, we may enter into price-risk-management transactions such as swaps, collars, futures and options to reduce our exposure to price declines associated with a
portion of our natural gas and oil production and thereby achieve a more predictable cash flow. The use of these arrangements will limit our ability to benefit from increases in the prices of natural gas and oil. In addition, our hedging
arrangements may apply only to a portion of our production, thereby providing only partial protection against declines in natural gas and oil prices. These arrangements could expose us to the risk of financial loss in certain circumstances,
including instances in which production is less than expected, our customers fail to purchase contracted quantities of natural gas and oil or a sudden, unexpected event materially adversely impacts natural gas or oil prices.

If oil and natural gas prices decrease, we may be required to take write-downs of the carrying values of our oil and natural gas
properties.

Certain accounting rules may require us to write down the carrying value of our properties when oil and
natural gas prices decrease or when we have substantial downward adjustments of our estimated proved reserves, increases in our estimates of development costs or deterioration in our exploration results. Once incurred, a write-down of our oil and
natural gas properties is not reversible at a later date. Any write-down would constitute a non-cash charge to earnings and could have a material adverse effect on our results of operations for the periods in which such charges are taken.

Our producing properties are located in regions that make us vulnerable to risks associated with operating in one major
contiguous geographic area, including, but not limited to, the risk of damage or business interruptions from hurricanes.

Our properties are located onshore and in state waters along the Texas and Louisiana Gulf Coast region of the United States. As a result
of this geographic concentration, we are disproportionately affected by any delays or interruptions in production or transportation in these areas caused by governmental regulation, transportation

capacity constraints, natural disasters, regional price fluctuations or other factors. This is particularly true of our inland water drilling and offshore operations, which are susceptible to
hurricanes and other tropical weather disturbances. Such disturbances have in the past and will in the future have any or all of the following adverse effects on our business:



interruptions to our operations as we suspend production in advance of an approaching storm;



damage to our facilities and equipment, including damage that disrupts or delays our production;



disruption to the transportation systems we rely upon to deliver our products to our customers; and

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damage to or disruption of our customers facilities that prevents us from taking delivery of our products.

Our identified drilling locations are scheduled out over several years, making them susceptible to uncertainties that could
materially alter the occurrence or timing of their drilling.

Our management has specifically identified and scheduled
drilling locations as an estimation of our future multi-year drilling activities on our existing acreage. These scheduled drilling locations represent a significant component of our growth strategy. Our ability to drill and develop these locations
depends on a number of uncertainties, including oil and natural gas prices, the availability of capital, costs, drilling results, regulatory approvals and other factors. Because of these uncertainties, we do not know if the potential drilling
locations we have identified will ever be drilled or if we will be able to produce oil or natural gas from these or any other potential drilling locations. As such, our actual drilling activities may materially differ from those presently
identified, which could adversely affect our business.

Market conditions or the unavailability of satisfactory
oil and natural gas transportation arrangements may hinder our access to oil and natural gas markets or delay our production. The availability of a ready market for our oil and natural gas production depends on a number of factors, including the
demand for and supply of oil and natural gas and the proximity of our reserves to pipelines and terminal facilities. Our ability to market our production depends in substantial part on the availability and capacity of transport vessels, gathering
systems, pipelines and processing facilities owned and operated by third parties under interruptible or short-term transportation agreements. Under the interruptible transportation agreements, the transportation of our natural gas may be interrupted
due to capacity constraints on the applicable system, for maintenance or repair of the system, or for other reasons as dictated by the particular agreements. Our failure to obtain such services on acceptable terms could materially harm our business.
We may be required to shut in wells due to lack of a market or the inadequacy or unavailability of natural gas pipeline or gathering system capacity. If that were to occur, we would be unable to realize revenue from those wells unless and until we
made arrangements for delivery of their production to market.

The continued threat of terrorism and the impact of military and other government
action have led and may lead to further increased volatility in prices for oil and natural gas and could affect these commodity markets or the financial markets used by us. In addition, the U.S. government has issued warnings that energy assets may
be a future target of terrorist organizations. These developments have subjected our oil and natural gas operations to increased risks. Any future terrorist attack on our facilities, those of our customers, the infrastructure we depend on for
transportation of our products, and, in some cases, those of other energy companies, could have a material adverse effect on our business.

The trading price of our common stock and the price at which we may sell common stock in the future could be subject to large fluctuations
in response to a variety of events or conditions, including, but not limited to, any of the following:

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limited trading volume in our common stock;

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quarterly variations in operating results;

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our involvement in litigation;

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general financial market conditions;

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the prices of natural gas and oil;

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announcements by us and our competitors;

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our liquidity;

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our ability to raise additional funds; and



changes in government regulations.

We do not intend to pay dividends on our common stock and our ability to pay dividends on our common stock is restricted.

We have not historically paid a dividend on our common stock, cash or otherwise, and do not intend to do so in the foreseeable future. We
are currently restricted from paying dividends on our common stock by our Senior Secured Notes Indenture dated December 22, 2011, and by our New Credit Agreement. Any future dividends also may be restricted by our then-existing debt agreements.

Provisions of Delaware law and our charter and bylaws may delay or prevent transactions that would benefit
stockholders.

Our certificate of incorporation and bylaws and the Delaware General Corporation Law, (the
DGCL), contain provisions that may have the effect of delaying, deferring or preventing a change of control of the Company. These provisions, among other things, authorize the Companys board of directors to set the terms of
preferred stock.

Because of these provisions, persons considering unsolicited tender offers or other unilateral takeover
proposals may be more likely to negotiate with our board of directors rather than pursue non-negotiated takeover attempts. As a result, these provisions may make it more difficult for our stockholders to benefit from transactions that are opposed by
our board of directors.

Sales of a substantial number of shares of our common stock, or the perception that such sales could occur, could
adversely affect the market price of our common stock by introducing a large number of sellers to the market. As of January 15, 2013, the selling stockholders named under Selling Security Holders own approximately 95% of our common
stock and may sell all or a portion of our common stock held by such Selling Security Holders (including sales by way of this prospectus and the registration statement of which it forms a part or otherwise). Such sales could cause the market price
of common stock to decline. We cannot predict whether future sales of our common stock, or the availability of our common stock for sale, will adversely affect the market price for our common stock or our ability to raise capital by offering equity
securities.

We may issue shares of preferred stock that could adversely affect holders of shares
of our common stock.

Our board of directors is authorized to issue additional classes or series of shares of preferred
stock without any action on the part of the holders of our common stock, subject to the limitations of our certificate of incorporation and the DGCL. Our board of directors also has the power, without approval of the holders of the shares of our
common stock and subject to the terms of our certificate of incorporation and the DGCL, to set the terms of any such classes or series of shares of preferred stock that may be issued, including voting rights, dividend rights, conversion features,
preferences over shares of our common stock with respect to dividends or if we liquidate, dissolve or wind up our business and other terms. If we issue shares of preferred stock in the future that have a preference over shares of our common stock
with respect to the payment of dividends or upon our liquidation, dissolution or winding up, or if we issue shares of preferred stock with voting rights that dilute the voting power of shares of our common stock, the rights of holders of shares of
our common stock or the trading price of shares of our common stock could be adversely affected.

OUR COMPANY

Overview

Dune Energy, Inc., a Delaware corporation, is an independent
energy company based in Houston, Texas. We were formed in 1998 and since May of 2004, we have been engaged in the exploration, development, acquisition and exploitation of crude oil and natural gas properties, with interests along the
Louisiana/Texas Gulf Coast. Our properties cover over 86,000 gross acres across 22 producing oil and natural gas fields.

Detailed Business
Information

For detailed information about our business and properties, please see the documents incorporated by reference
in this prospects, as listed on page 25.

Our Business Strategy

We intend to use our competitive strengths to increase reserves, production and cash flow in order to maximize value for our stockholders.
The following are key elements of this strategy:

Grow Through Exploitation, Development and Exploration of Our
Properties. Our primary focus will continue to be the development and exploration efforts in our Gulf Coast properties. We believe that our properties and acreage position will allow us to grow organically through low-risk drilling in the near
term, as this property set continues to present attractive opportunities to expand our reserve base through workovers and recompletions, field extensions, delineating deeper formations within existing fields and higher risk/higher reward exploratory
drilling. In addition, we will constantly review, rationalize and high-grade our properties in order to optimize our existing asset base.

Actively Manage the Risks and Rewards of Our Drilling Program. Our strategy is to increase our oil and natural gas reserves and production while keeping our finding and development costs and
operating costs (on a per Mcfe basis) competitive with our industry peers. We expect to implement this strategy through drilling exploratory and development wells from our inventory of available prospects that we have evaluated for geologic and
mechanical risk and future reserve or resource potential. Our drilling program will contain some higher risk/higher reserve potential opportunities as well as some lower risk/lower reserve potential opportunities in order to achieve a balanced
program of reserve and production growth.

Maintain and Utilize State of the Art Technological Expertise. We expect to
maintain and utilize our technical and operations teams knowledge of salt-dome structures and multiple stacked producing zones common in the Gulf Coast to enhance our growth prospects and reserve potential. We employ technical

advancements, including 3-D seismic data, pre-stack depth and reverse-time migration, to identify and exploit new opportunities in our asset base. We also employ the latest directional drilling,
completion and stimulation technology in our wells to enhance recoverability and accelerate cash flows.

Pursue
Opportunistic Acquisitions of Underdeveloped Properties. We continually review opportunities to acquire producing properties, leasehold acreage and drilling prospects that are in core operating areas and require a minimum of initial upfront
capital. We are also seeking to acquire operational control of properties that we believe have a solid proved reserve base coupled with significant exploitation and exploration potential. We will evaluate acquisition opportunities that we believe
will further enhance our operations and reserves in a cost-effective manner.

The common stock to be offered and sold pursuant to this prospectus will be offered and sold by the selling stockholders. We will not
receive any proceeds from the sale of the common stock by the selling stockholders.

PRIVATE
PLACEMENT OF COMMON STOCK

On December 21, 2012, we issued 18,749,997 shares of our common stock in the amounts and
to the parties identified below (the Investors), pursuant to a Stock Purchase Agreement (collectively the Stock Purchase Agreements and such transaction the Financing) between the company and each such
stockholder, resulting in gross proceeds to the company of $30,000,000 (the Initial Closing). Upon our election, and subject to our meeting certain performance objectives, we may conduct two additional closings with the Investors prior
to December 31, 2013 (each a Subsequent Closing). In each Subsequent Closing, we will issue up to 6,250,000 shares of our common stock at a purchase price of $1.60 per share or a total purchase price of up to $10,000,000. The
Investors may also elect to require us to conduct a closing in which we will issue the remaining shares to be issued in the Financing, upon the occurrence of certain events specified in the Stock Purchase Agreements.

The shares of common stock being offered by the selling stockholders are those previously issued to the Selling Security Holders. For
additional information regarding the issuances of common stock, see Private Placement of Common Shares above. All information in the following table and related footnotes has been supplied to us by the selling stockholders, and we have
relied on their representations.

We are including the shares of common stock in order to permit the selling stockholders to
offer the shares for resale from time to time. The selling stockholders have not had any material relationship with us within the past three years except for (i) the ownership of the shares of common stock and (ii) certain matters related
to Stephen P. Kovacs, a former director of the company. On September 10, 2012, Stephen P. Kovacs, commenced employment with Strategic Value Partners, LLC, an affiliate of Mardi Gras Ltd., High Ridge Ltd. and Strategic Value Special Situation
Fund, L.P. as a Managing Director. At that time, Mr. Kovacs resigned from the companys Audit Committee. Mr. Kovacs did not participate in the meetings or negotiations related to the Financing. Mr. Kovacs resigned from the
companys board of directors on January 8, 2013.

The table below lists the selling stockholders and other
information regarding the beneficial ownership of the shares of common stock by each of the selling stockholders. The first column lists the names of the selling stockholders. The second column lists the number of shares beneficially owned by each
selling stockholder prior this offering.

The third column lists the maximum number of shares of common stock being offered by
this prospectus by the selling stockholders.

In accordance with the terms of a registration rights agreement with the holders
of the shares of common stock, this prospectus generally covers the resale of at least the number of shares of common stock issued pursuant to the Stock Purchase Agreements. The fourth column lists the number of shares that will be beneficially
owned by each selling stockholder and the percentage of the outstanding common stock of the company such shares represent, assuming the sale of all of the shares offered by the selling stockholders pursuant to this prospectus. The percentage of
common stock owned is based on 59,021,389 shares of our common stock outstanding as of January 15, 2013.

The selling
stockholders may sell all, some or none of their shares in this offering. See Plan of Distribution. Unless otherwise indicated, all information contained below is as of January 15, 2013.

The address of Simplon Partners, L.P. is 1 Rockefeller Plaza, Suite 1712, New York, NY 10020. Thomas A. McKay exercises voting and dispositive power over the securities
held by Simplon Partners, L.P.

(2)

The address of Simplon International Limited is 1 Rockefeller Plaza, Suite 1712, New York, NY 10020. Thomas A. McKay exercises voting and dispositive power over the
securities held by Simplon International Limited.

(3)

The address of Highbridge International, LLC is ATTN: Chris Casale 40 West 57th Street, 32nd Floor New York, NY, 10019. Highbridge Capital Management, LLC is the
trading manager of Highbridge International, LLC and has voting and dispositive power over the securities held by Highbridge International, LLC. Glenn Dubin is the Chief Executive Officer of Highbridge Capital Management, LLC. Each of Highbridge
Capital Management LLC and Glenn Dubin disclaims beneficial ownership of the securities held by Highbridge International LLC.

(4)

The address of West Face Long Term Opportunities Global Master L.P. is c/o West Face Capital Inc., 810-2 Bloor Street East, Box #85, Toronto,
Ontario M4W 1A8. West Face Capital Inc. (West Face Capital), which is the Advisor to West Face Long Term Opportunities Global Master L.P. (Global Master Fund), exercises voting and dispositive power over the securities held
by Global Master Fund. Voting and

investment decisions of West Face Capital are made by its Co-Chief Investment Officers, Gregory Boland and Peter Fraser, each of whom disclaims beneficial ownership of any shares held by Global
Master Fund.

(5)

The address of BlueMountain Distressed Master Fund L.P. is Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands. Ethan Auerbach, Andrew
Feldstein and Derek Smith exercise voting and dispositive power over the securities held by BlueMountain Distressed Master Fund L.P.

The address of BlueMountain Timberline Ltd. is Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands. Ethan Auerbach, Andrew Feldstein and Derek
Smith exercise voting and dispositive power over the securities held by BlueMountain Timberline Ltd.

(10)

The address of BlueMountain Kicking Horse Fund L.P. is Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands. Ethan Auerbach, Andrew Feldstein
and Derek Smith exercise voting and dispositive power over the securities held by BlueMountain Kicking Horse Fund L.P.

The address of BlueMountain Credit Opportunities Master Fund I L.P. is Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands. Ethan Auerbach,
Andrew Feldstein and Derek Smith exercise voting and dispositive power over the securities held by BlueMountain Credit Opportunities Master Fund I L.P.

(13)

The address of Zell Credit Opportunities Side Fund, L.P. (ZCOF) is Two North Riverside Plaza, Suite 600, Chicago, IL, 60606. ZCOF is a Delaware limited
partnership. Chai Trust Company, LLC, an Illinois limited liability company (Chai), is the general partner and investment manager of ZCOF. The following individuals are the Senior Managing Directors of Chai: Robert M. Levin, Donald J.
Liebentritt, Jonathan D. Wasserman, JoAnn Zell, Kellie Zell and Matthew Zell.

The address of TPG Opportunity Fund I, L.P. (Opportunity I) is 301 Commerce Street, Suite 3300, Fort Worth, TX, 76102. Opportunity Is
general partner is TPG Opportunities Advisors, Inc., a Delaware corporation (Opportunities Advisors). David Bonderman and James G. Coulter are officers, directors and sole shareholders of Opportunities Advisors and therefore may be
deemed to beneficially own the shares held by Opportunity I. Messrs. Bonderman and Coulter disclaim beneficial ownership of the shares held by Opportunity I except to the extent of their pecuniary interest therein. The address of Opportunities
Advisors

The address of TPG Opportunity Fund III, L.P. (Opportunity III) is 301 Commerce Street, Suite 3300, Fort Worth, TX, 76102. Opportunity IIIs general
partner is Opportunities Advisors. David Bonderman and James G. Coulter are officers, directors and sole shareholders of Opportunities Advisors and therefore may be deemed to beneficially own the shares held by Opportunity III. Messrs. Bonderman and
Coulter disclaim beneficial ownership of the shares held by Opportunity III except to the extent of their pecuniary interest therein. The address of Opportunities Advisors and Messrs. Bonderman and Coulter is c/o TPG Global, LLC, 301 Commerce
Street, Suite 3300, Fort Worth, TX 76102.

The address of High Ridge Ltd. is c/o Strategic Value Partners, LLC, 100 West Putnam Avenue, Greenwich, CT 06830. Victor Khosla, the Chief Investment Officer of
Strategic Value Partners, LLC, indirectly exercises voting and dispositive power over the securities held by High Ridge Ltd. Mr. Khosla disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

We are registering for resale the shares of common stock previously issued pursuant to the Stock Purchase Agreements to
permit the resale of these shares of common stock by the holders of the common stock from time to time after the date of this prospectus. We will not receive any of the proceeds from the sale by the selling stockholders of the shares of common
stock. We will bear all fees and expenses incident to our obligation to register for resale the shares of common stock.

The
selling stockholders may sell all or a portion of the shares of common stock beneficially owned by them and offered hereby from time to time directly or through one or more underwriters, broker-dealers or agents. If the shares of common stock are
sold through underwriters or broker-dealers, the selling stockholders will be responsible for underwriting discounts or commissions or agents commissions. The shares of common stock may be sold in one or more transactions at fixed prices, at
prevailing market prices at the time of the sale, at varying prices determined at the time of sale, or at negotiated prices. These sales may be effected in transactions, which may involve crosses or block transactions,



on any national securities exchange or quotation service on which the securities may be listed or quoted at the time of sale;

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in the over-the-counter market;

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in transactions otherwise than on these exchanges or systems or in the over-the-counter market;

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through the writing of options, whether such options are listed on an options exchange or otherwise;

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ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

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block trades in which the broker-dealer will attempt to sell the shares as agent but may position and resell a portion of the block as principal to
facilitate the transaction;

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purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

an exchange distribution in accordance with the rules of the applicable exchange;

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privately negotiated transactions;

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short sales;

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broker-dealers may agree with the selling stockholders to sell a specified number of such shares at a stipulated price per share;



a combination of any such methods of sale; and

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any other method permitted pursuant to applicable law.

If the selling stockholders effect such transactions by selling shares of common stock to or through underwriters, broker-dealers or agents, such underwriters, broker-dealers or agents may receive
commissions in the form of discounts, concessions or commissions from the selling stockholders or commissions from purchasers of the shares of common stock for whom they may act as agent or to whom they may sell as principal (which discounts,
concessions or commissions as to particular underwriters, broker-dealers or agents may be in excess of those customary in the types of transactions involved). In connection with sales of the shares of common stock or otherwise, the selling
stockholders may enter into hedging transactions with broker-dealers, which may in turn engage in short sales of the shares of common stock in the course of hedging in positions they assume. The selling stockholders may also sell shares of common
stock short and deliver shares of common stock covered by this prospectus to close out short positions and to return borrowed shares in connection with such short sales. The selling stockholders may also loan or pledge shares of common stock to
broker-dealers that in turn may sell such shares.

The selling stockholders may pledge or grant a security interest in some or
all of the shares of common stock owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the shares of common stock from time to time pursuant to this prospectus or any
amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act of 1933, as amended, amending, if necessary, the list of selling stockholders to include the pledgee, transferee or other successors in interest as
selling stockholders under this prospectus. The selling stockholders also may transfer and donate the shares of common stock in other circumstances in which case the transferees, donees, pledgees or other successors in interest will be the selling
beneficial owners for purposes of this prospectus.

The selling stockholders and any broker-dealer participating in the
distribution of the shares of common stock may be deemed to be underwriters within the meaning of the Securities Act, and any commission paid, or any discounts or concessions allowed to, any such broker-dealer may be deemed to be
underwriting commissions or discounts under the Securities Act. At the time a particular offering of the shares of common stock is made, a prospectus supplement, if required, will be distributed which will set forth the aggregate amount of shares of
common stock being offered and the terms of the offering, including the name or names of any broker-dealers or agents, any discounts, commissions and other terms constituting compensation from the selling stockholders and any discounts, commissions
or concessions allowed or reallowed or paid to broker-dealers.

Under the securities laws of some states, the shares of common
stock may be sold in such states only through registered or licensed brokers or dealers. In addition, in some states the shares of common stock may not be sold unless such shares have been registered or qualified for sale in such state or an
exemption from registration or qualification is available and is complied with.

There can be no assurance that any selling
stockholder will sell any or all of the shares of common stock registered pursuant to the shelf registration statement, of which this prospectus forms a part.

The selling stockholders and any other person participating in such distribution will be subject to applicable provisions of the Securities Exchange Act of 1934, as amended, and the rules and regulations
thereunder,

including, without limitation, Regulation M of the Exchange Act of 1934, as amended, which may limit the timing of purchases and sales of any of the shares of common stock by the selling
stockholders and any other participating person. Regulation M may also restrict the ability of any person engaged in the distribution of the shares of common stock to engage in market-making activities with respect to the shares of common stock. All
of the foregoing may affect the marketability of the shares of common stock and the ability of any person or entity to engage in market-making activities with respect to the shares of common stock.

We will pay all expenses of the registration of the shares of common stock pursuant to the registration rights agreement, estimated to be
$87,155.94 in total, including, without limitation, Securities and Exchange Commission filing fees and expenses of compliance with state securities or blue sky laws; provided, however, that a selling stockholder will pay all underwriting
discounts and selling commissions, if any. We will indemnify the selling stockholders against liabilities, including some liabilities under the Securities Act, in accordance with the registration rights agreements, or the selling stockholders will
be entitled to contribution. We may be indemnified by the selling stockholders against civil liabilities, including liabilities under the Securities Act, that may arise from any written information furnished to us by the selling stockholder
specifically for use in this prospectus, in accordance with the related registration rights agreement, or we may be entitled to contribution.

Once sold under the shelf registration statement, of which this prospectus forms a part, the shares of common stock will be freely tradable in the hands of persons other than our affiliates.

In the event of a material change in the plan of distribution disclosed in this prospectus, the selling stockholders will not be able to
effect transactions in the shares pursuant to this prospectus until such time as a post-effective amendment to the registration statement is filed with and declared effective by the SEC.

DESCRIPTION OF CAPITAL STOCK

The following summary is a description of the material terms of our capital stock. This summary is not intended to be a complete description of our capital stock, and it is subject in all respects to
the applicable provisions of Delaware law and of our constituent documents and of the constituent documents of our subsidiaries. For more information, please review our Amended and Restated Certificate of Incorporation, as amended, and our Amended
and Restated By-laws.

General

Our authorized capital stock consists of 4,200,000,000 shares of common stock, $.001 par value per share and 1,000,000 shares of preferred stock, $.001 par value per share. No preferred shares are
designated and outstanding as of the date of this prospectus.

Common Stock

As of January 15, 2013, there were 59,021,389 shares of our common stock outstanding, which were held by an estimated 117 record
owners. Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders and do not have cumulative voting rights. Accordingly, holders of a majority of the shares of our common stock
entitled to vote in any election of directors may elect all of the directors standing for election. Subject to the right of holders of any preferred stock then outstanding, holders of our common stock are entitled to receive proportionately any
dividends if and when such dividends are declared by our board of directors. Upon the liquidation, dissolution or winding up of the company, the holders of our common stock are entitled to receive ratably our net assets available after the payment
of all debts and other liabilities. Holders of our common stock have no non-contractual preemptive, subscription, redemption or conversion rights.

Our board of directors may, without stockholder approval, issue preferred stock from time to time as shares of one or more classes or series. Subject to the provisions of our Amended and Restated
Certificate of Incorporation and limitations prescribed by law, the board of directors is expressly authorized to issue the shares, fix the number of shares, change the number of shares constituting any series, and provide for or change the voting
powers, designations, preferences and relative, participating, optional or other special rights, qualifications, limitations or restrictions thereof, including dividend rights (including whether dividends are cumulative), dividend rates, terms of
redemption (including sinking fund provisions), redemption prices, conversion rights, and liquidation preferences of the shares constituting any class or series of the preferred stock, in each case without any further action or vote by the
stockholders and subject to the terms of our preferred stock.

One of the effects of undesignated preferred stock may be to
enable our board of directors to render more difficult or to discourage an attempt to obtain control of our Company by means of a tender offer, proxy contest, merger or otherwise, and thereby to protect the continuity of our management. The issuance
of shares of the preferred stock pursuant to the board of directors authority described above may adversely affect the rights of the holders of common stock. For example, preferred stock issued by us may rank prior to common stock as to
dividend rights, liquidation preference or both, may have full or limited voting rights and may be convertible into shares of common stock. Accordingly, the issuance of shares of preferred stock may discourage bids for common stock or may otherwise
adversely affect the market price of common stock.

Delaware Anti-Takeover Law

The Company is subject to the provisions of Section 203 of the Delaware General Corporation Law regulating corporate takeovers. In
general, Section 203 prohibits a publicly-held Delaware corporation from engaging, under certain circumstances, in a business combination with an interested stockholder for a period of three years following the time the person became an
interested stockholder unless:



prior to the time the person became an interested stockholder, the board of directors of the corporation approved either the business combination or
the transaction which resulted in the stockholder becoming an interested stockholder;



upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the stockholder owned a least 85% of the voting
stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding (but not the outstanding stock owned by the interested stockholder) those (1) shares owned by persons
who are directors and also officers and (2) shares owned by employee stock plans in which employee participants do not have the right to determine confidentiality whether shares held subject to the plan will be tendered in a tender or exchange
offer; or



at or subsequent to the time the person became an interested stockholder, the business combination is approved by the board of directors and authorized
at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock which is not owned by the interested stockholder.

The application of Section 203 may limit the ability of our stockholders to approve a transaction that they may deem to be in their
interests. Under Section 203, a business combination generally includes a merger, asset or stock sale, or other similar transaction with an interested stockholder, and an interested stockholder is generally
a person who, together with its affiliates and associates, owns or, in the case of affiliates or associates of the corporation, owned 15% or more of a corporations outstanding voting securities within three years prior to the determination of
interested stockholder status.

The SEC allows us to incorporate by reference into this prospectus certain information that we file with it, which means that we can
disclose important information to you by referring you to that information. The information incorporated by reference is considered to be a part of this prospectus. We incorporate by reference the documents listed below (other than information
furnished under Items 2.02 or 7.01 of any Form 8-K, which is not deemed filed under the Exchange Act):



our Annual Report on Form 10-K for the year ended December 31, 2011, as filed with the SEC on March 23, 2012;

our Quarterly Report on Form 10-Q for the period ended March 31, 2012, as filed with the SEC on May 3, 2012;



our Quarterly Report on Form 10-Q for the period ended June 30, 2012, as filed with the SEC on August 1, 2012;



our Quarterly Report on Form 10-Q for the period ended September 30, 2012, as filed with the SEC on November 2, 2012;



our Current Reports on Form 8-K filed on January 13, 2012; January 23, 2012; January 30, 2012; March 6, 2012, as
amended by the Form 8-K/A filed on April 20, 2012; March 29, 2012; May 3, 2012; June 5, 2012; August 1, 2012; August 9, 2012; September 25, 2012; September 27, 2012; November 20,
2012; December 24, 2012; December 27, 2012; January 9, 2013; and January 16, 2013.

We will provide copy of any of these filings at no cost upon your written request directed to Dune Energy, Inc., Two Shell Plaza, 777
Walker Street, Suite 2300, Houston Texas, 77002, Attention: Investor Relations or upon your oral request made by calling our Investor Relations department at (713) 229-6300.

We also make available free of charge on our internet website at http://www.duneenergy.com our annual reports on Form 10-K, quarterly
reports on Form 10-Q and current reports on Form 8-K, and any amendments to those reports, as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. Information contained on our website is not part
of this prospectus.

LEGAL MATTERS

Legal matters in connection with the validity of the shares offered by this prospectus have been passed upon by DLA Piper LLP (US),
Austin, Texas.

EXPERTS

The financial statements of Dune at December 31, 2011 and 2010 and accompanying footnotes incorporated by reference in this
prospectus and registration statement have been audited by MaloneBailey, LLP, independent registered public accounting firm, as set forth in their report thereon appearing elsewhere herein, and are incorporated in reliance upon such report, given on
the authority of such firm as experts in accounting and auditing.

Certain estimates of net total oil and natural gas reserves
and the PV-10 value of such reserves as of June 30, 2012 incorporated by reference in this prospectus are based in part on a reserve report prepared by DeGolyer and MacNaughton, an independent petroleum engineering firm.

Our expenses in connection with the issuance and distribution of the securities being registered, other than any underwriting discount, are estimated as follows:

SEC Registration Fee

$

4,155.94

Legal Fees and expenses

$

75,000

Accountants Fees and Expenses

$

8,000

Miscellaneous Expenses

$

0

Total

$

87,155.94

Item 14.

Indemnification of Directors and Officers

Section 145(a) of the DGCL empowers a corporation to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that the person is or was a director, officer, employee or agent of the corporation, or is or was serving at
the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys fees), judgments, fines and amounts paid in
settlement actually and reasonably incurred by the person in connection with such action, suit or proceeding if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the
corporation, and, with respect to any criminal action or proceeding, had no reasonable cause to believe the persons conduct was unlawful. The termination of any action, suit or proceeding by judgment, order, settlement, conviction, or upon a
plea of nolo contendere or its equivalent, shall not, of itself, create a presumption that the person did not act in good faith and in a manner which the person reasonably believed to be in or not opposed to the best interests of the corporation,
and, with respect to any criminal action or proceeding, had reasonable cause to believe that the persons conduct was unlawful.

Section 145(b) of the DGCL empowers a corporation to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the
right of the corporation to procure a judgment in its favor by reason of the fact that the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or other enterprise against expenses (including attorneys fees) actually and reasonably incurred by the person in connection with the defense or settlement of such
action or suit if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made in respect of any claim, issue or matter
as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or the court in which such action or suit was brought shall determine upon application that, despite the
adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem proper.

Section 145(c) of the DGCL provides that to the extent that a present or former director or officer of a corporation has been
successful on the merits or otherwise in defense of any action, suit or proceeding referred to in subsections (a) and (b) of Section 145, or in defense of any claim, issue or matter therein, such person shall be indemnified against
expenses (including attorneys fees) actually and reasonably incurred by such person in connection therewith.

Section 145(d) of the DGCL provides that any indemnification under subsections (a) and (b) of Section 145 (unless
ordered by a court) shall be made by the corporation only as authorized in the specific case upon a determination that indemnification of the present or former director, officer, employee or agent is proper in the

circumstances because the person has met the applicable standard of conduct set forth in subsections (a) and (b) of Section 145. Such determination shall be made, with respect to a
person who is a director or officer at the time of such determination, (1) by a majority vote of the directors who are not parties to such action, suit or proceeding, even though less than a quorum, or (2) by a committee of such directors
designated by majority vote of such directors, even though less than a quorum, or (3) if there are no such directors, or if such directors so direct, by independent legal counsel in a written opinion, or (4) by the stockholders.

Section 145(e) of the DGCL provides that expenses (including attorneys fees) incurred by an officer or director in
defending any civil, criminal, administrative or investigative action, suit or proceeding may be paid by the corporation in advance of the final disposition of such action, suit or proceeding upon receipt of an undertaking by or on behalf of such
director or officer to repay such amount if it shall ultimately be determined that such person is not entitled to be indemnified by the corporation as authorized in Section 145. Such expenses (including attorneys fees) incurred by former
directors and officers or other employees and agents may be so paid upon such terms and conditions, if any, as the corporation deems appropriate.

Section 145(f) of the DGCL provides that the indemnification and advancement of expenses provided by, or granted pursuant to, the other subsections of Section 145 shall not be deemed exclusive
of any other rights to which those seeking indemnification or advancement of expenses may be entitled under any bylaw, agreement, vote of stockholders or disinterested directors or otherwise, both as to action in such persons official capacity
and as to action in another capacity while holding such office.

Section 145(g) of the DGCL provides that a corporation
shall have power to purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise against any liability asserted against such person and incurred by such person in any such capacity, or arising out of such persons status as such, whether or not the
corporation would have the power to indemnify such person against such liability under Section 145.

Section 145(j)
of the DGCL provides that the indemnification and advancement of expenses provided by, or granted pursuant to, Section 145 shall, unless otherwise provided when authorized or ratified, continue as to a person who has ceased to be a director,
officer, employee or agent and shall inure to the benefit of the heirs, executors and administrators of such a person.

Section 102(b)(7) of the DGCL provides that a certificate of incorporation may contain a provision eliminating or limiting the
personal liability of a director to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director, provided that such provision shall not eliminate or limit the liability of a director: (i) for any breach
of the directors duty of loyalty to the corporation or its stockholders; (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law; (iii) under Section 174 of the DGCL or
(iv) for any transaction from which the director derived an improper personal benefit. In accordance with Section 102(b)(7) of the DGCL, our Amended and Restated Certificate of Incorporation contains a provision that generally eliminates
the personal liability of directors for monetary damages for breaches of their fiduciary duty, subject to the limitations of Section 102(b)(7).

Furthermore, our Amended and Restated Certificate of Incorporation and Bylaws provide for (i) indemnification of our directors, officers and employees and agents (to the extent deemed appropriate by
the board of directors) to the fullest extent permitted by applicable law; (ii) the right of our directors, officers, employees and agents to be paid or reimbursed by us for the reasonable expenses incurred in advance of a proceedings
final disposition to the fullest extent authorized by applicable law; and (iii) the purchase of insurance by us to protect us and any person who is or was serving as our director, officer, employee or agent.

In addition, we have entered into indemnification agreements with each of our directors. The indemnification agreements provide that the
Company will indemnify each person subject to an indemnification

agreement (each, an Indemnified Party) to the fullest extent permitted by applicable law against all expenses, judgments, penalties, fines and amounts paid in settlement of certain
proceedings that may result or arise in connection with such Indemnified Party serving in his capacity as an officer or director of the Company, or is or was serving at the request of the Company as an officer, director, employee or agent of another
entity. The indemnification agreements further provide that, upon an Indemnified Partys request, the Company will advance expenses to the Indemnified Party. Pursuant to the indemnification agreements, an Indemnified Party is presumed to be
entitled to indemnification and anyone seeking to overcome this presumption has the burden of proving otherwise.

We maintain
insurance policies that provide coverage to our directors and officers against certain liabilities.

Item 15.

Recent Sales of Unregistered Securities

On December 21, 2012, we issued 18,749,997 shares of our common stock in the amounts and to the parties identified below (the Investors), pursuant to a Stock Purchase Agreement
(collectively the Stock Purchase Agreements and such transaction the Financing) between the company and each such stockholder, resulting in gross proceeds to the company of $30,000,000 (the Initial Closing). Upon
our election, and subject to our meeting certain performance objectives, we may conduct two additional closings with the Investors prior to December 31, 2013 (each a Subsequent Closing). In each Subsequent Closing, we will issue up
to 6,250,000 shares of our common stock at a purchase price of $1.60 per share or a total purchase price of up to $10,000,000. The Investors may also elect to require us to conduct a closing in which we will issue the remaining shares to be issued
in the Financing, upon the occurrence of certain events specified in the Stock Purchase Agreements.

The shares of common
stock were issued in reliance on an exemption from registration under Section 4(2) of the Securities Act. The proceeds from the sale of common stock will be used to fund working capital and repay indebtedness.

The exhibits
listed on the Exhibit Index to this registration statement are hereby incorporated by reference.

Item 17.

Undertakings

A. The
undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by
section 10(a)(3) of the Securities Act;

(ii) To reflect in the prospectus any facts or events arising after
the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement.
Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum
offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the
Calculation of Registration Fee table in the effective registration statement; and

(iii) To
include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in this registration statement.

(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall
be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which
remain unsold at the termination of the offering.

(4) That, for the purpose of determining any liability
under the Securities Act to any purchaser, each prospectus filed pursuant to Rule 424(b) as part of a registration statement relating to an offering, other than registration statements relying on Rule 430B or other than prospectuses filed in
reliance on Rule 430A, shall be deemed to be part of and included in the registration statement as of the date it is first used after effectiveness; provided, however, that no statement made in a registration statement or prospectus that is part of
the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior
to such first use, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such date of first use.

(5) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers
and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is,
therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful
defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by
controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized,
in the City of Houston, State of Texas, on January 18, 2013.

Amended and Restated Certificate of Incorporation (incorporated by reference to Exhibit 3.1 to the Registrants Form 10-KSB (File No. 001-32497) for the year ended December 31,
2002).

3.1.1

Certificate of Amendment of Amended and Restated Certificate of Incorporation, dated May 7, 2003 (incorporated by reference to Exhibit 3.1.1 the Registrants Form 10-K (File
No. 001-32497) for the year ended December 31, 2010).

3.1.2

Certificate of Amendment of Certificate of Incorporation, dated May 5, 2004 (incorporated by reference to Exhibit 3.1 to the Registrants Form 10-Q (File No. 001-32497) for the
period ended March 31, 2007).

3.1.3

Certificate of Amendment of Certificate of Incorporation, dated June 12, 2007 (incorporated by reference to Exhibit 3.1.3 to the Registrants Form 10-K (File No. 001-32497) for
the year ended December 31, 2010).

3.1.4

Certificate of Amendment of Certificate of Incorporation, dated December 14, 2007 (incorporated by reference to Exhibit 3.1.4 to the Registrants Form 10-K (File No. 001-32497)
for the year ended December 31, 2010).

3.1.5

Certificate of Amendment of Amended and Restated Certificate of Incorporation, dated December 1, 2009 (incorporated by reference to Exhibit 3.1.2 to the Registrants
Current Report on Form 8-K (File No. 001-32497) filed on December 1, 2009).

3.1.6

Certificate of Amendment of Amended and Restated Certificate of Incorporation, dated December 22, 2011 (incorporated by reference to Exhibit 3.2 to the Registrants Form
8-K (File No. 001-32497) filed on December 27, 2011).

3.2

Amended and Restated By-Laws (incorporated by reference to Exhibit 3.1 to the Registrants Report on Form 8-K (File No. 001-32497) filed on July 12, 2010).

Indenture, dated December 22, 2011 by and among Dune Energy, Inc. and U.S. Bank National Association (incorporated by reference to Exhibit 4.2 to the Registrants Current
Report on Form 8-K (File No. 001-32497) filed on December 27, 2011).

4.3

Collateral Agreement, dated December 22, 2011, by and among Dune Energy, Inc. and U.S. Bank National Association (incorporated by reference to Exhibit 4.3 to the Registrants
Current Report on Form 8-K (File No. 001-32497) filed on December 27, 2011).

4.4

Second Lien Mortgage (incorporated by reference to Exhibit 4.4 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 27, 2011).

4.5

Indenture, dated May 15, 2007, among the Company, each of Dune Operating Company and Vaquero Partners LLC, as guarantors, and The Bank of New York, as trustee and collateral agent
(incorporated by reference to Exhibit 4.1 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on May 21, 2007).

First Supplemental Indenture, dated December 30, 2008, by and among Dune Energy, Inc, the guarantors signatory thereto and The Bank of New York Mellon (incorporated by reference to
Exhibit 4.1 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 30, 2008).

4.7

Second Supplemental Indenture, dated as of December 21, 2011, by and among Dune Energy, Inc., the guarantors signatory thereto and The Bank of New York Mellon (incorporated by
reference to Exhibit 4.1 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 27, 2011).

Employment Agreement, effective October 1, 2012, between Dune Energy, Inc. and James A. Watt (incorporated by reference to Exhibit 10.1 to the Registrants Form 8-K (File No.
000-27897) filed on September 25, 2012).

Form of Grant Agreement under Dune Energy, Inc. 2007 Stock Incentive Plan (incorporated by reference to Exhibit 10.7 to the Registrants Form 10-K (File No. 001-32497) for the
year ended December 31, 2010).

10.6

Amended and Restated Credit Agreement, dated December 22, 2011, among Dune Energy, Inc., Bank of Montreal, CIT Capital Securities LLC and the lenders party thereto (incorporated by
reference to Exhibit 10.1 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 27, 2011), as amended in the First Amendment to the Amended and Restated Credit Agreement dated September 25, 2012 (incorporated by
reference to Exhibit 10.1 to the Registrants Form 8-K (File No. 000-27897) filed on September 27, 2012) (collectively, the New Credit Agreement).

10.7

Amended and Restated Guarantee and Collateral Agreement (incorporated by reference to Exhibit 10.2 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on
December 27, 2011).

Amended and Restated Mortgage (incorporated by reference to Exhibit 10.3 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 27,
2011).

10.9

Master Assignment of Note and Liens, dated as of December 22, 2011 (incorporated by reference to Exhibit 10.4 to the Registrants Current Report on Form 8-K (File No.
001-32497) filed on December 27, 2011).

10.10

Intercreditor Agreement (incorporated by reference to Exhibit 10.5 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on December 27,
2011).

10.11

1992 ISDA Master Agreement, together with Schedule, dated May 15, 2007 among Wells Fargo Foothill, Inc. and the Company (incorporated by reference to Exhibit 99.1 to the
Registrants Current Report on Form 8-K (File No. 001-32497) filed on June 25, 2010).

10.12

Purchase and Sale Agreement, dated as of May 28, 2010, between Dune Properties, Inc., as Seller, and Texas Petroleum Investment Company, as Buyer (incorporated by reference to
Exhibit 10.6 to the Registrants Current Report on Form 8-K (File No. 001-32497) filed on May 21, 2007).

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